1. Field of the Invention
The present invention relates to a continuous vacuum treatment system such as a system for continuously vacuum-drying fabric yarns kept in spindle-shaped blocks after dying them, a high-speed drying system for ceramic products or vacuum-dried foods, a system for continuously vacuum-depositing a film of different material on a surface of an unbendable or unwindable article such as a sheet of glass or a thick plastic plate, or the like.
2. Description of the Prior Art
One example of a heretofore known system for drying articles by making use of hot air is shown in vertical cross section in FIG. 18. In this figure, reference numeral 03 designates a casing, numeral 04 designates a drainboard-like intermediate wall provided with the casing 03, numeral 05 designates a feed pipe for feeding hot air 07, and numeral 06 designates an exhaust gas pipe for exhausting cold air 08 after drying. In the hot air drying system constructed in the above-described manner, articles to be dried 01 accommodated in containers 02 having drainboard-like bottom walls are charged, and hot air 07 is fed thereto from a hot air generator not shown. The articles to be dried 01 are heated and dried by the hot air 07 blowing through interstices of the articles to be dried 01.
The drying system relying upon hot air gives rise to the problems indicated. That is, because a packed condition of the articles to be dried 01 within the container 02 is liable to occur, there exists a location where hot air 07 can well blow therethrough and a location where it can hardly blow therethrough, resulting in poor quality (insufficient drying) or an elongation of the time necessitated for drying. Therefore, if the temperature of hot air is raised in order to shorten the drying time, sometimes the articles to be dried 01 would be changed in quality.
For the purpose of resolving the aforementioned problems, a vacuum drying system as shown in FIG. 19 has been devised. In this figure, reference numeral 013 designates a vacuum chamber, numeral 013a designates a manhole, numeral 015 designates an evacuation device for evacuating the air inside of the vacuum chamber 013 numeral 016 designates an evacuation duct for connecting the evacuation device 015 with the vacuum chamber 013, and numeral 017 designates a heat source of a dielectric heating type or the like. Articles to be dried 011 are charged within the containers 012 at the outside of the vacuum chamber 013, they are accommodated jointly with the containers 012 within the vacuum chamber 013, after the manhole 013a has been closed the inside of the vacuum chamber 013 is evacuated by the evacuation device 015, and the articles to be dried 011 are heated and dried by the heat source 017 of a dielectric heating type or the like. After drying is completed, the inside of the vacuum chamber 013 is returned to the atmosphere, and after the containers 012 have been taken out and articles to be dried 011 have been recharged therein, the containers are returned into the vacuum chamber, and these steps of processing are repeatedly executed. An efficiency rate of operation is 50% or less.
In the above-described vacuum drying system in the prior art, since the system is of batch type wherein the steps of charging, evacuation, drying, pressure recovery and take-out are repeated, an efficiency rate of operation is as low as 50% or less. Also, in the process relying upon hot air a treatment time for one batch is long compared to the vacuum drying system, and also uneven drying as well as a degradation in quality caused by local overheating would arise.